Neuro 10.3 Strokes Flashcards
What is the definition of a stroke?
The damaging or killing of brain cells starved of oxygen as a result of the blood supply to that part of the brain being cut off
What is a TIA?
A stroke that recovers within 24 hours from the onset of symptoms
Name possible locations for origins of clots
- carotid arteries
- vertebral/basilar arteries
- heart: valvular disease/AF
- the aorta
What is encompassed by the anterior circulation and posterior circulation?
- Fed by internal carotid
- Encompasses the ACA and MCA
- Fed from vertebral arteries
- Encompasses: PCA, cerebellar arteries, arteries supplying the brainstem
In anterior circulation:
- What artery has been affected?
- What area of brain does it supply?
- What does this part of brain do?
- Anterior cerebral artery
- supplies: medial aspects of frontal and parietal lobe and anterior part of corpus callosum
- supplies motor and sensory function to lower limb and genitals
How will a patient present in anterior cerebral artery stroke?
- Motor loss: contralateral, lower limb affected more than upper limb, initially get flaccid paralysis followed later by spasticity (UMN signs)
- Sensory loss: contralateral, loss of all sensory modalities in the lower limb (spinothalamic and dorsal column affected equally)
What are two important areas to know about when talking about Ant cerebral artery strokes?
- Paracentral lobules: area of medial cortex that controls voluntary portion of mircturition, damage leads to loss of voluntary control
- Corpus callosum: damage to ACA can lead to split brain syndrome/alien hand syndrome
Middle cerebral artery strokes
-what area does the brain supply?
- Superior temporal lobe, lateral aspects of frontal and parietal lobe
- basal ganglia, internal capsule, macular cortex
Middle cerebral artery strokes
- what does this part of the brain do?
- what occurs in main trunk occlusions?
- MCA supplies all of the homonculus not supplied by ACA (not legs or genitals)
- MTOs cause considerable cerebral oedema - may lead to coma/death
Middle cerebral artery strokes
-How will the patient present?
- Motor loss: contralateral, upper limb and face affected more than lower limb. Initially get flaccid paralysis followed later by spasticity (UMN signs)
- Sensory loss: contralateral, loss of all sensory modalities in the upper limb and face.
Middle cerebral artery strokes
-Why is the location of occlusion important?
- Proximal occlusion: will affected lateral motor cortex and internal capsule (carries descending motor fibres from the enterito of the motor cortex), t/f face, arm and leg may be affected (lenticulostriate arteries are affected)
- More distal occlusion (after lenticulostriate arteries): spares the internal capsule but still damages the lateral motor cortex t/f only arm and face are affected
Middle cerebral artery strokes
-What are the visual effects?
- Proximal occlusion of MCA: contralateral homonymous hemianopia (temporal and parietal radiations are lost)
- Distal occlusion of MCA: contralateral homonymous superior or inferior quadrantonopia (very rare)
Middle cerebral artery strokes
-how is speech affected?
- Speech centres normally reside in LHS of brain, but symptoms depend on which branch of MCA is affected and which is the dominant hemisphere
- If dominant hemisphere is affected
- Proximal occlusion: global aphasia caused by main trunk occlusion
- Distal occlusion: Brocca’s (expressive) alphasia (leads to motor loss) and/or Wernicke’s (receptor) aphasia (pt speaks rubbish)
Middle cerebral artery strokes
-Speech: what happens if the non-dominant (right is most likely) side is affected?
- Get hemispatial neglect
- tacticle extinction: touch both sides together - get extinction of LHS stimulus
- visual extinction
- Anosognosia
- *Are without Disease knowledge and deny they have any form of disability
Posterior cerebral artery
-What area of the brain does it supply?
-inferior temporal lobe and occipital lobe
Posterior cerebral artery
-What does this area of the brain do? How will the patient present?
- Contains the visual cortex
- In stroke, the patent will present with contralateral homonymous hemianopia with macular sparing
Anterior Cerebellar artery stroke
- What does this part of the brain do?
- How will the patient present?
- Coordinates all movements
- Disdiadochokinesia, Ataxia, Nystagms, Intention tremor, slurred speech and hypotonia
What do the cerebellar arteries also supply? What is the difference between a proximal and distal occlusion of the cerebellar arteries?
- The brainstem
- A proximal occlusion may cause brainstem and cerebellar signs (eg pontine infarction is proximal)
- A distal occlusion may cause cerebellar signs alone
What sort of deficits will you have if you damage brain supply to the brainstem?
- Will damage ascending/descending tracts affecting the contralateral side of the body
- The cranial nerve nuclei are located in brainstem so damage to them will cause ipsilateral signs
Basilar artery strokes
-What area is affected?
-Same area as posterior cerebral artery - inferior temporal lobes and posterior cerebral artery.
Basilar artery strokes
-What will a distal occlusion cause?
- Bilateral occipital lobe infarction: pt becomes blind
- bilateral thalamic infarction: pt is anaesthetised
- Bilateral midbrain infarction: affects cranial nerves
- Any stroke involving the basilar artery will cause bilateral symptoms because we only have 1 basilar artery
Basilar artery strokes
-What will a proximal occlusion cause?
- Locked in syndrome: get pontine artery occlusion, corti-cospinal pathway in ventral pons leads to quadrapledia
- Lose cortico-bulbar pathway (pyramidal tract
- Retain consciousness and ascending sensory info
Lacunar strokes - lenticulostriate artery
- What is this a branch of?
- What part of the brain does it supply?
- What does this part of body do?
- MCA
- Internal capsule (carries down motor fibres to supply body muscles) and basal ganglia
- The posterior limb carries descending motor fibres
Lenticulostriate artery strokes
-How will the patient present?
- Isolated (to 1 side), contralateral paralysis
- Initially will be flaccid, followed by spasticity
- Involves face, upper limb and lower limb
Left thalamoperforator artery stroke
- What is this a branch of?
- What part of the brain does it supply?
- What does this part of body do?
- small branch of PCA
- Supplies part of the thalamus
- The thalamus relays sensory information to the post-central gyrus (somatosensory cortex)
Left thalamoperforator artery stroke
-How will the patient present?
-Isolated (to 1 side), contralateral sensory loss (all modalities) in the face, upper limb and lower limb
What imaging modality is best for strokes and timings?
- CT is best for acute phase - helps find the bleed
- MRI is better for post-acute phase (takes too long for acute phase)
What are things that could mimic a stroke?
- Hypoglycaemia
- epilepsy
- migraine (hemiplegic)
- intracranial tumours/infections
